In radio frequency (RF) transmission, multiple bursts of data may be transmitted over a common transmission medium between a plurality of simultaneous users. For practical purposes, a burst of data is equivalent to a packet of data. Each user's transmission may or may not interfere with that of the other users, depending on the transmission protocol that is utilized. A requirement of an effective RF receiver is that the device both successfully demodulate legitimate bursts of data and correctly discard received bursts that contain excessive noise or interference. Bursts containing only noise or interference should also be rejected. Moreover, the receiver should achieve accurate time synchronization for legitimate bursts of information.
Burst or packet data acquisition in digital receivers is often unreliable and expensive to perform, primarily due to the amount of noise and interference that often accompanies a data signal. Burst detection “falses” and “misses” lead to lower data communications throughput and increased packet error rates. A “false” is defined as an event where the digital receiver incorrectly classifies the received signal as a valid data burst when it is not valid, and a “miss” is defined as an event where the digital receiver undesirably misses (or fails to detect) a valid received data burst.
In many communications systems, traditional burst detection methods typically exclusively utilize either a lower modulation order detection (e.g., biphase shift keying or BPSK), or a higher modulation order detection (e.g., quadrature phase shift keying or QPSK) for burst sync word detection. However, using either a lower modulation order (e.g., BPSK) or a higher modulation order (e.g., QPSK) sync word detection method in an attempt to optimize both the miss and false rate performance of the receiver has inherent drawbacks. Typically, one parameter (e.g., the miss rate) must be optimized or improved at the expense of the other parameter (e.g., the false rate). Many traditional receivers also rely on detected signal energy to detect bursts, which is also highly susceptible to noise and interference problems, further negatively impacting packet or bit error rate (PER or BER), and falsing rate performance.
Therefore, a need exists for a high performance and relatively inexpensive method for reducing both the falsing and the miss rates that often contribute to the decreased data throughput and unreliability of communication in traditional digital receivers.